This backup would be useless only if you burn an efuse after this point. I have the same reason for backing mine up I think. I'd like to play online in the future possibly, but in the meantime I can knock out the 20 single player games I downloaded. That should keep me busy until Pokemon comes out, and I suspect there will be a (preventative) solution to online bans by then as well.I'm doing it because if i want to go online again, i just restore it (it will be a PITA) and don't worry about bans. But whatever, i don't see myself paying for online play.
If i update, this backup will be useless, right? (I'm now on 5.1.0, but in future updates)